Method for improving the filling ability of tobacco

ABSTRACT

The invention relates to a method for improving the fillability of tobacco, as tobacco leaves or ribs and/or tobacco additives, by treatment of the tobacco material, which has approx. up to 15 wt. % initial moisture with a treatment gas consisting of nitrogen and/or argon at pressures of 50 to 1,000 bar with continuous or graduated compression followed by continuous or graduated decompression, with the compression and decompression stages taking place in either one autoclave or with cascade-type switching in several autoclaves, followed by thermal after-treatment of the tobacco material discharged, which is characterised in that the compression is carried out at an operating temperature above 55° C., preferably at 60 to 90° C. and the initial moisture of the tobacco material lies within the range 8 to 14 wt. %.

[0001] The invention relates to a method for improving the fillabilityof tobacco, as cut tobacco leaves or ribs and/or tobacco additives, bytreatment of the tobacco material, which initially has up to 15 wt. %moisture with a treatment gas consisting of nitrogen and/or argon atpressures of 50 to 1,000 bar with continuous or graduated compressionfollowed by continuous or graduated decompression, in which thecompression or decompression stages take place in either an autoclave orwith cascade-type switching in several autoclaves, followed by thermalafter-treatment of the tobacco material discharged.

[0002] Methods of this kind, which are also known as INCOM expansionmethods, have proved to be advantageous compared with the pressuretreatment of tobacco with carbon dioxide, ammonia or volatile organicgases. Thus DE 31 19 330 A1 describes such an expansion method withoperating temperatures of 0 to 50° C. prevailing in the autoclave,wherein to increase the fillability or the degree of expansion, use of atobacco material with moisture of up to 15 wt. % and after-treatmentwith water vapour was provided. In this case the aim was that lowermoisture of the tobacco of 10 to 15 wt. % would lead to a desiredgreater cooling of the tobacco material to be discharged when thetension was released.

[0003] Furthermore, DE 34 14 625 C2 discloses a cascade method,according to which, by the most widely varying measures such as coolingof the treatment gas before loading of the reactor, cooling of theautoclaves or use of an undercooled and liquefied treatment gas, a lowoperating temperature is to be effected during impregnation of thetobacco. It is true that the tobacco moisture may lie anywhere, forinstance within the range of 10-30 wt. %, however it is expresslyrequired that the autoclave temperature and/or its cooling watertemperature must not exceed 50° C.

[0004] This is also confirmed according to DE 39 35 774 C2 in connectionwith a cascade-type expansion method, in which circulation of thetreatment gas via a cooler is provided, in order to keep to thenecessary low impregnation temperatures of 25 or 45° C.

[0005] Although good values have already been achieved with theaforementioned expansion methods with regard to increasing thefillability of tobacco and/or the degree of expansion, these arerelatively expensive because of the necessary cooling of the autoclaveor autoclaves and because of the additional cooling of the treatmentgas.

[0006] The aim of the invention is to improve the existing INCOM methodsand with equally good or better values with regard to fillability orexpansion effect, to avoid the uneconomical cooling measures duringcompression which have hitherto been regarded as necessary.

[0007] According to the invention a method of the type initiallymentioned according to the preamble to the patent claim, is thereforeproposed, which is characterised by the fact that the compression iscarried out at a reactor temperature of above 55° C.

[0008] Surprisingly it has transpired that in the case of low tobaccomoistures within the range of up to 15 wt. % the existing theory, whichrequires a low treatment temperature, does not lead to optimum expansionresults. On the contrary, only by increasing the treatment temperatureduring compression was it possible to achieve surprisingly good valueswith regard to the expansion effect and/or fillability.

[0009] Furthermore, according to the method, this leads to theadvantage, that the heat of compression does not have to be eliminated,and thus no additional cooling of the autoclave or autoclaves isnecessary.

[0010] In the following example, the method according to the inventionis explained in comparison with the existing state of the art. The testresults show the differing influence of the operating temperature on thedegree of expansion for different tobacco moistures. According to theexisting theory, in the case of tobacco moisture of 18 wt. %, increasingthe operating temperature above 40° C. leads to a deterioration in theexpansion effect. On the other hand, in the case of tobacco moistures ofbelow 15 wt. %, clear improvements appear if the high pressure treatmentis carried out at operating temperatures of 60 and 80° C. Surprisinglythe achievable degrees of expansion with low tobacco moisture and higheroperating temperatures are even in some cases above the values achievedunder conventional conditions.

EXAMPLE

[0011] The high pressure treatment was carried out in a laboratoryautoclave with a used content of 2l . A casing for circulation of liquidmedia was used to adjust the desired operating temperatures. Thebuild-up of pressure was carried out from below, the reduction inpressure upwards. Several valves made the intended circuit diagramspossible. A compressor was used to adjust the final pressure. Athermocouple element measured the tobacco temperature in the uppertobacco filling section.

[0012] The laboratory device for thermal after-treatment consisted of apermeable wire gauze serving as a conveyor belt, baffles for formationof the tobacco mat in the desired width, a steam nozzle with slit-typeoutlet and a steam suction device arranged under the belt. Theafter-treatment was carried out with saturated steam.

[0013] The most important treatment parameters are shown by thefollowing Table 1. TABLE 1 High pressure treatment Thermalafter-treatment Gas supply from below Steaming about 10 kg/h capacityGas outlet upwards Slit nozzle about 8 mm Tobacco 300 g Slit width about160 mm quantity Tobacco PVC pipe/ Transport about 5 cm/s containerperforated bottom

[0014] The tobacco samples were spread out in flat plastic trays andconditioned in the standard climate at 21° C. and 62% relative humidity.The fillabilities were determined using a Borgwaldt density meter, andthe specific volume in ml/g converted for a nominal moisture of 12 wt. %and a nominal temperature of 22° C. From the data of the untreatedcomparison/base specimens and the expanded specimens, the relativeimprovement in fillability, which is also described as the degree ofexpansion, can be calculated according to the following formula, inwhich F_(B) means the fillability of the base and F_(E) means thefillability of the expanded tobacco:

Δ%=(F _(E) −F _(B))*100%/F _(B)

[0015] The tests were carried out with tobacco moistures of 8, 12 and 14and 18 wt. % as a comparison. The operating temperatures were adjustedby thermostatic control to 40, 60 and 80° C. The final pressure amountedto 700 bar, the pressure reduction was carried out in a time interval ofapprox. 0.5 min. All the tests were based on a uniform mixture ofVirginia tobaccos and the after-treatment method with saturated steamdescribed.

[0016] The results of the tests are represented in the following Table2, and those of the comparative test in the following Table 2a. In thetables T_(A) means the tobacco temperature immediately before removalfrom the autoclave as discharge temperature and Δ% means the relativeimprovement in fillability and/or degree of expansion. TABLE 2 Tobaccomoisture 8 wt. % Tobacco moisture 12 wt. % Tobacco moisture 14 wt. %Operating temperature ° C. T_(A) ° C. Δ % T_(A) ° C. Δ % T_(A) ° C. Δ %40 −61 59 −53 70 −48 76 60 −48 70 −25 79 −18 83 80 −15 78 −3 81 0 73

[0017] TABLE 2a Tobacco moisture 18 wt. % Operating temperature ° C.T_(A) ° C. Δ % 40 −41 80 60 −12 76 80 1 54

[0018] Comparison of the above tables clearly shows the positive effectof higher operating temperatures of 60 and 80° C. on the improvement offillability, if tobacco with moistures of less than 15 wt. % is used.

1. Method for improving the fillability of tobacco, as cut tobaccoleaves or ribs and/or tobacco additives, by treatment of the tobaccomaterial, which has up to approx. 15 wt. % initial moisture with atreatment gas consisting of nitrogen and/or argon at pressures of 50 to1,000 bar with continuous or graduated compression followed bycontinuous or graduated decompression, the compression or decompressionstages being carried out in either one autoclave or with cascade-typeswitching in several autoclaves, followed by thermal after-treatment ofthe tobacco material discharged, characterised in that the compressionis carried out at an operating temperature above 55° C.
 2. Methodaccording to claim 1, characterised in that the compression is carriedout at an operating temperature of 60 to 90° C.
 3. Method according toclaim 1, characterised in that the initial moisture of the tobaccomaterial lies within the range 8 to 14 wt. %.